Cholesterol Solubility in Bile. EVIDENCE THAT SUPERSATURATED BILE IS FREQUENT IN HEALTHY MAN

TLDR

The study develops and validates a direct method to measure maximum cholesterol solubility in bile. The authors employed this direct measurement approach and in vitro bile‑model solutions to determine the micellar zone of cholesterol solubility. The method revealed that human bile is frequently supersaturated with cholesterol, with a smaller micellar zone than previously reported, and that while supersaturation is necessary, it alone does not explain gallstone formation.

Abstract

The development and validation of a direct method for measuring maximum cholesterol solubility in bile is described. Application of this method to five large mammalian species, including man, produced a micellar zone significantly smaller than that previously reported. Further studies on in vitro model solutions patterned after bile confirmed this new micellar zone. Thus, direct evidence demonstrates that the micellar zone boundary derived in vitro from model solutions is applicable to human gallbladder bile. Using the present criteria, normal human bile, in contrast to bile from other mammalian species, is commonly supersaturated with cholesterol. A male-female difference in bile composition is not demonstrable despite the well-established female preponderance of cholelithiasis. Bile from patients with cholesterol cholelithiasis has a micellar zone similar to normals but differs compositionally in that there is a greater excess of cholesterol above saturation. We conclude that cholesterol supersaturation may be a necessary but not solely sufficient cause for gallstone formation.